Power transmission apparatus



- 2g w3? R. K. PEPPER ET Ax.

POWER TRANSMISSION APARATUS Filed May 2l. 1935 2 Sheets-Shee 1 ImvEHTnRSDc- 28? 19:57u R. K. PEPPER ET AL 20379 POWER TRANSMISSION APPARATUSFiled May 2l, 1935 2 Sheets-Sheet 2 WITNESS 10 Patented Dec. 28, 1937UNITED STATES PATENT OFFICE POWER TRANSMISSION APPARATUS Robert K.Pepper and Samuel C. V. Pepper, Syracuse, N. Y.

Application May 21, 1935, Serial Naeass s 5 claims. (c1. 19a-3o) and tocause the same to move in unison in Y This invention relates to a powertransmission apparatus and pertains more particularly to a clutch orcoupling mechanism for operatively connecting and disconnecting Ythedrive and driven elements. Y

In the Voperation of large heavy machinery such as commonly used in roadbuilding or other large contract work such as tractors, locomotivecranes, power operated shovels or the like, and particularly in allcases where the source of power is derived from units not easily, oradapted to be, operated in a reverse direction such as steam turbines,Diesel engines, and so forth, it has heretofore been customary, insofaras the applicants are aware, to incorporate in the transmissionmechanism positive clutches having elements movable relatively towardandfrom each other into and out of clutching engagement such as the commonjawclutch. These-jaw clutches are very unsatisfactory to operate for thereason that it is difficult and sometimes impossible to bring the clutchelements into clutching engagement with each other while the drive unitis in operation. Thus, it is often necessary to entirely stop theoperation of the drive unit or to reduce the speed of operation thereofto such an extent as to greatly impair the efficiency of the operationof the device and for the further reason that the teeth of the jawclutch elements are of short-life, re'-` quiring frequent replacement,which is very costly both in time and labor. l

The main object of this invention is to provid a simply constructed andoperated power drive mechanism, peculiarly adapted for use with internalcombustion engines, steamA turbines or the like, which depend uponarelatively high speed to obtain maximum efficiency.

Another object ofthe inventionv is to provide a' power transmissionmechanism having incorporated therein a positive clutch mechanism whichmay be quickly Vand'easily moved into and'yout of the clutching positionwithout' discontinuing or excessively retarding the operation'of thedrive unit. Y

Another object of the invention is to provide a power transmissionapparatus of the above mentioned class having a clutch mechanism adaptedto be encased in a lubricant or which willV be equally effective whetherexposed to water or other liquids or when operatingasra dry clutch.

A further object is to produce a positive clutch mechanism includingclutch elements permanently connected to permit relative movementthereof` in one plane as when inthe declutchingpositicn another plane aswhen being moved to and from the clutching position and which, wheninthe idling or de-clutching position, will operate with a minimumamount of friction.

A still further object of the invention is to provide a clutch mechanismfor a power transmission apparatus which is simple, durable, andeconomical in construction and operation.

Furthermore, we have provided a simply constructed clutch mechanismcomprising relatively movable members which are always maintained inpredetermined relationship with each other and which are moved in unisonrelatively to the v drive and driven members to bring the same into andout of the clutching position, thereby producing a positive clutch meanswhich may be as readily operated when' the drive member is in operationas when said member is at rest.

Other objects and advantages pertaining to the construction of thedevice and to the form and relation of the parts thereof will more fullyappear from the following description taken in connection with theaccompanying drawings in which:

Figure v1 is a perspective view of a power trans'- mission apparatusembodying the various features of this invention. l

Figure 2is anhoriaontal sectional view taken through the upper portionof the transmission case substantially in the plane of the line 2-2,

Figure 3. Y Y

Figure Bris a vertical sectional view taken on line 33, Figure 2, on anenlarged scale.

Figure 4 is a detail sectional view taken on line 44, FigureS.

Figure 5 is a transverse sectional View taken on line 5 5, Figure 3,illustrating the major portion of our novel clutch mechanism inelevation.

Figure 6 is a detail longitudinal sectional view taken substantially/,atright angles -to the View illustrated in Figure 3, upon line 6-6 of saidfigure.

Figure 8 is a detail vertical sectional View taken- 1 on line 88, Figure2. Figure 9 is a plan view on a reduced scale of a modified form ofclutch mechanism.

Figure l0 is a sectional View, partly in elevation, taken substantiallyon line Ill-lll, Figure v9. As shown inthe drawings, our novelV power,transmission apparatus preferably comprises a v substantially liquid oroil-tight case or housing I including a body portion 2 and a cover 3removably secured to the upper side of the body 2. A drive shaft 4 and adriven shaft 5 are mounted in the case i in co-axial alignment. Theshafts may each, as shown, be journaled in suitable rolling bearingmembers 1 mounted in any suitable manner in the wall of the case I,whilestufng boxes 8 may be provided for each shaft for preventing the escapeof lubricant from the interior of the case about the respective shafts.The drive shaft 4 may be connected with any suitable source of powersuch as a steam turbine, an internal combustion engine or the like, andhas the inner end thereof terminating a short distance, in this instancewithin the case I, and is provided with a clutch drive member IU, which,in this instance, is in the form of a yoke or cup-shaped element andwhich may be secured to or made integral with the drive shaft 4. lThedriven shaft 5 is shown as extending inwardly through the case I and hasthe inner end thereof journaled in a suitable bearing II provided in theinner end of the shaft 4 or the adjacent portion of the clutch drivemember I0. Our novel clutch mechanism as i2 comprises primarily theclutch drive member I0, a clutch driven member or collar i3 and male andfemale clutch elements or rings I4 and I5 respectively.

The collar I3 is shown as being secured to the driven shaft 5 by meansof a pin I6 so that said collar and shaft will rotate in unison. It isobvious, however, that the collar may be made integral with the shaftwhen so desired. The collar I 3 is provided with a pair of diametricallyopposed outwardly extending studs or trunnions I8 which may be securedthereto or made integral therewith. The female clutch element, in thisinstance, comprises two similarly constructed ring sections I9 which aresecured together side by side by a plurality of, in this instance, sixbolts or their equivalents 2U arranged in uniform circumferential spacedrelation intermediate the outer and inner peripheral surface thereof.This female clutch element I5 is provided with a pair of di. ametricallyopposed recesses 2I which extend inwardly from the inner peripherythereof and adapted to rotatably receive therein a respective trunnionI3. rihe clutch element I5 is also provided with an annular recess orchannel 22 in the outer periphery thereof adapted to rotatably receivetherein the male clutch element I4 which, in this instance, has theouter periphery thereof of substantially the same diameter as the outerperiphery of the clutch element I5, but is of slightly less depth orradial width than the channel 22. Mounted in the bottom of the channel22 intermediate the clutch elements I4 and I5 are a multiplicity ofrolling members 23 which, in this instance, are in the form of rollersadapted to rotatably support the outer or male clutch element I4 duringthe relative rotary'movement of the clutch elements as when saidelements are in the neutral or declutching position.

The male clutch element I4 is provided with a pair of diametricallyopposed outwardly extending trunnions 25 which may be secured to or madeintegral with said clutch element. These trunnions extend outwardly fromthe clutching element I4 into respective bushings 26 which are mountedin the inner portion of the clutch drive member Ill in the followingmanner:

lThe peripheral wall of the clutch drive member or housing YIl) isprovided with a pair of diametrically opposed holes or apertures 21 ofsubstantially the same diameter as the body portion of the bushings 26.These apertures 21 are arranged in spaced relation to the inner sideedge of the drive member I and are connected therewith by reduced neckportions 21' which are substantially the same width as the diameter ofthe trunnions 25. When assembling the clutch element I 4 in the drivemember I0 the trunnions are rst inserted through the mouth portions 21into the apertures 21, after which the bushings 26 are inserted in theapertures over the trunnions 25. The bushings may be maintained in theapertures 21.by any suitable means as by a split ring 28 mounted in anannular groove provided in the periphery of the body portion of eachbushing and which are adapted to register in corresponding annulargrooves formed in the wall of each aperture 21 as will be readilyunderstood. In order that the clutch elements I 4 and I5 may be movedinto and I9 facing the interior of the case I is provided adjacent theouter periphery thereof with a pair of laterally disposed ears or lugs3i! which are arranged in a plane extending substantially at rightangles to the plane of the trunnion recesses 2 I.

Mounted between the lugs 3U is a shouldered stud 3| which is pivotallyconnected with the ears by means of a pin 32 which is mounted inregistering apertures or holes provided in the stud and ears. The stud3| is provided with a reduced cylindrical portion 3I' which extendsthrough an elongated radially disposed slot 33 provided in an annularflange or plate 34 secured to or made integral with a sleeve 35 which isslidably mounted upon the driven shaft 5. The length of the cylindricalportion 3| of the stud 3| is slightly greater than the width of theplate 34 and has mounted thereon a pair of wear shoes or washers 35positioned one adjacent either face of the plate 34. The stud 3I andshoes 36 are secured to the plate 34 by means of a nut 31 screw threadedon the outer reduced end of the stud 3l which is of slightly lessdiameter than the cylindrical portion 3| so that when the nut 31 istightly screw threaded against the' cylindrical portion 3 I the studwill be securely connected to the plate 34 and at the same time have afree sliding movement relative thereto. 'The nut 31 may be secured inthe holding position by any suitable means as a lock nut 39. The sleeve35 is also provided with an outwardly extendingr flange 4I) of slightlygreater diameter than that of the sleeve 35 and which is positioned inslightly spaced relation to the plate 34. Mounted upon the sleeve 35 isa second sleeve 42 of greater interior diameter than the exteriordiameter of the sleeve 35. The forward or inner end of the sleeve 42 isprovided with an inwardly extending annular ange 43 which is adapted tofreely slide over the sleeve 35 and is normally held into engagementwith the flange 40 by means of a coil spring 44 mounted upon the sleeve35 between the flange 43 and a nut 46 screw threaded on the outer end ofthe sleeve 35.

The sleeve 42 is provided with an annular recess or groove 41 in theouter periphery thereof intermediate its ends. In the groove 41 ispositioned the forked or bifurcated end 48 of an operating lever 49.This lever extends upwardly from the sleeves 35 and 42 through the cover3 and has the upper end thereof provided with a spherical handle 50 bywhich the lever may be manually actuated. The lever 49 also comprises aspherical portion I secured to or made integral therewith and which isadapted to be received in a circular recess 52 provided in the cover 3as illustrated in Figure 3. The ball or bearing memf in Figure 5 duringthe relative rotation thereof,

ber 5| is operatively maintained in the recess 52 by a retainer plate 53which is secured Aby screws o1' other suitable means to the lower faceof .the cover 3. 1

It will now be readily understood that by rocking the upper endofthelever50 toward yor from the driveshaft 4, that a corresponding slidingmovement of the sleeve k42 will be produced axially of the driven shaft5. This sliding movement of the sleeve 42 will be transmitted to thesleeve 35 and plate 34 through the medium of the spring 44 and it isobvious'that as theV plate 34 is moved axially along the shaft 5towardand from the trunnions I8 and 25 the clutch elements i4 and I5 will berocked in unison thereby about the axes of the trunnions I8 and 25 asapivot when said trunnions Aare in or approaching substantially the samediametrical plane as illustrated in Figure 5.

In order that the sleeves 35 and 42 may be releasably maintained ineither of two extreme positions against vibratory movement, the sleeve35 is provided with a spring-pressed ball 55 mounted in a radiallydisposed recess 56 provided at one side of the plate 34, said ball beingadapted to engage one or Vthe other of a pair :of axially spacedsemi-circular recesses 51 provided in the periphery of the driven shaft5 as illustrated in Figure 3. l

It will now be understood that when the clutch elements I4 and I5 are ina position substantially normal to the axis of movement of the drive`shaft 4 and driven shaft 5 as illustrated by full lines in Figures 3 and6, the drive clutch element `III will freely rotate about the drivenclutch element I5, thereby permitting' free' relative rotary movement ofthe drive and driven shafts. Furthermore, it will be observed that thisrelative rotation of the clutch elements will be effected with a minimumamount of friction, due to the fact that these elements mayefiicaciously be operated in oil, and also due to the provision of therolling bearing members 23 intermediate the clutch elements. It is to beunderstood, however, that the bearing members 23 may be dispensed withwithout materially affecting the operation of the clutch elements,particularly where the transmission is of relatively light structure,lbut when the mechanism is built relatively large and strong fo-r heavyduty work, these bearing members are preferably used to reduce thefriction between the clutch elementsduring the relative rotary movementthereof, inasmuch as the elements are supported one upon the other.

Considering .now that the clutch elements or rings I4 and I5 are in thede-clutching position, as shown by full lines in Figure 6, the driveshaft and clutch member l0 connected therewith are being rotated, thenwhen the lever 49 is rocked about its pivot 5| rto move the` sleeve 42in a direction away from the clutch` elements I4 Yand I5, the tensionthus produced upon the spring 44 will be transmitted to the inner sleeve35 and to that side of the clutch element I5 to which the stud 3I isattached, thereby urging the element I5 to swing about the trunnions I8as a pivot from a position normal to the axis of the driven shaft 5 toan inclined position at an angle thereto. This swinging or pivotalmovement of the clutch element I5 and also of the clutch element I4will, of course, not take 'place if `and when the trunnions I8 and 25 ofsaid elements are in a position substantially at right angles to eachother. However, as these trunnions approach or reach an alignedposition, asl indicated it is apparent lthat the clutch elements I4 andI5v will be free to swing to an inclined angular position relative tothe axis ofv movement of thev clutch members I0 and I3, o-r shafts 4 and5.

`,It has been found by experimentation that the degree of this swingingmovement of the clutch elements to effect a `direct vdrive therethroughfrom one clutch member I0 or `I3 to the other, may vary within certainlimits. preferable vthat the clutch elements or rings be ,inclined at anangle of substantially 45 degrees It is, however,V

, TheY reason for the relatively easy manner in which the clutchelements or rings may be moved to and from the clutching position seemsto be due to the following operation of the parts which may possiblybermore readily understood by referring to Figure 7 iii-connection withthe structure shown in Figures 3, 5, and 6. In Figure '7 the line X-Xrepresents the axis of rotation of the ldrive and'driven members and theclutch elements or ringsf|4 and I5 connected therewith. The line Y--Yrepresents the'plane normal to the'axis of rotation of the clutchelements or rings occupied by said clutch elements when in thede-clutching or idling position.` The line Z--Z represents the plane ofinclination of the clutch elements when these members are in theclutching or operative position. D represents the drive clutch member aslil. The arrow F represents the force applied to the drive clutchelement D. The arrow R represents the resistance offered by the drivenclutch element and A the angle of travel of the clutch elements duringthe swing- Ving movement thereof to and from the clutchingposition. Y

It will now be apparent that when the clutch elements` I 4` and I5V arein the inclined position represented by the. line Z-Z and force isapplied as at F, the line of direction of the force will Vaxially causedby the inclined relation of the clutch elements I4 and I5 to the normalpath of movement of the trunnions will be opposed by the clutch drivemember Ii! so that rotation of the drive trunnions or pivots as 25 willbe in a plane normal to the axis of rotation X-X with v the result thatmotion is transmitted from the drive clutchelement to the driven clutchelement for producing rotation thereof in unison. Also, it will beunderstood that the greatest or nearly all the stress uponthe clutchelements caused during the drive action therebetween occurs in theimmediate vicinity of the pivots or Ytrunnions 25fand I8 and that thenearer the axis of rotation X-X the line of inclination of the clutchelements as Z-Z approaches, the less is the tendency of the forceapplied to the elements to produce swinging of the clutch elements'toward the plane Y-Y or line of travel of the force.

It has been found by actual practice that when the angle of inclinationof the clutch elements approaches 45 to the axis of rotation thereof,the friction between the drive and driven elements or rings is more thansuicient to prevent said clutch elements being returned by the coactionof the driving force and the inclined relation of the clutch elementsthereto to the idling position in a plane normal to the axis of rotationthereof. However, this friction between the clutch elements and betweenthe pivots or trunnions 25 and I8 and the associated members insofarashas been determined, is never so much more than the action of the forcetending to move the clutch elements from the inclined plane but that therings are easily moved by applying a relatively small force to the sideof the rings at right angles to the axis of swinging movement thereof asby the stud 3|.

Furthermore, inasmuch as the clutch rings are not under load when in theidling or declutching position as when lying in the plane of the lineY-Y they are very easily swung about their inner and outer pivots I8 and25, when said pivots are in or are nearly in co-axial alignment, fromthe idling or de-clutching position to the clutching or operativeposition.

In order that motion may be transmitted from the drive shaft 4 to thedriven shaft 5 for producing rotation of the driven shaft in a directionopposite to that of the drive shaft or for producing rotation of thedriven` shaft at different speed from that of the drive shaft there isillustrated in Figure 2 a simple power transmission mechanism utilizingthe novel clutch mechanism above described for producing these results.In the structure shown more particularly in Figures 2 and 3, it will benoted that the clutch drive member I is provided with a substantiallyfiat end wall I0 to which is secured as by rivets 58 or theirequivalent, a gear member 66. At each side of the driven shaft ismounted a secondary drive shaft 6 I. The secondary shafts 6 I arearranged in substantially parallel relation with each other and with thedriven shaft 5 and have the ends thereof journaled in suitable bearings62 provided in the wall of the case I as illustrated more clearly inFigure 8. Upon each shaft 6I at the end thereof adjacent the drive gearSII is rotatably mounted a gear member 63. Each gear member 63 may, asshown in Figure 8, be mounted upon a rolling bearing 64 which, in turn,is mounted upon a reduced portion of the shaft 6I. These gear members 63are, as illustrated in Figure 2, substantially the same diameter as thegear 60 and are in constant meshing engagement with said latter gear.

'I'o each of the gears 63 is secured a positive clutch mechanismconstructed and operated in the manner described for the clutchmechanism I2 associated with the drive and driven shafts 4 and 5 so thatmotion may be transmitted from the gears 63 to the respective secondaryshafts 6I as desired. To the opposite end of one of the secondary shafts6I is secured a gear 65 which is of greater pitch diameter than the gear63 associated with said shaft. This gear 65 is in meshing engagementwith a gear 66 which is secured to the driven shaft 5 and which is ofsmaller pitch diameter than either the gear 65 or gears 6I! and 53. Tothe other secondary shaft 6I is secured a gear member 61 ofsubstantially the same pitch diameter as the gear 66 and which isoperatively connected with said gear 66 through the medium of an idlergear 68 which is j ournaled on a stub shaft 69 secured to the adjacentpor# tion of the wall of the case I in any suitable manner.

It will be obvious that the shaft 6I having the gear 65 connectedtherewith is an over-drive shaft by which the driven shaft 5 may beoperated in the same direction as when driven directly by the driveshaft 4 but which will drive the driven shaft 5 at an increased speedover that of said drive shaft. Also, it will be noted that the othersecondary shaft 6I and the mechanism associated therewith constitute areverse drive by which the driven shaft 5 may be driven at the samespeed of the drive shaft 4 but in the reverse direction from that ofsaid drive shaft. It will now be obvious that inasmuch as the drivenshaft 5 may be connected with any suitable mechanism said mechanism andthe driven shaft may be operated from the drive shaft 4. either bydirect drive or at an increased speed over that of the drive shaft or ina reverse direction to that of the drive shaft without retarding thespeed of the drive shaft 4 or the power unit operating said drive shaftby merely manipulating one of the clutch mechanisms I2 depending uponthe action desired.

While we have shown in Figure 2 a simple arrangement by which motion maybe transmitted in various relations from a drive member to a drivenmember, it is to be understood that we do not wish to be limited to theexact construction shown therein or the arrangement of the parts thereofas it is obvious that many other combinations of shaft and geararrangements may be readily provided for producing the required result.However, in each instance it will be noted that motion may not only betransmitted from the drive shaft to the driven shaft without retardingor completely stopping the operation of the drive shaft and the powerunit connected therewith, but each gear member is always in meshingengagement with a cooperating gear member so that at no time is itnecessary to engage or disengage one or more gear members, therebyproviding a mechanism wherein the teeth of the gears may be constructedto the greater advantage to obtain a maximum efficiency both in powerand in quietness of operation.

In Figures 9 a-nd 10 there is illustrated a slight modication of ournovel clutch mechanism as illustrated in the remaining figures. In thestructure shown in these two figures the main difference or distinctionlies in the fact that one of the sets of pivotal members or trunnions as25 for the clutch elements or rings is mounted in correspondingelongated slots 'II provided in the respective clutch drive member as12. These slots 'II extend from the. plane extending through the otherpivot members or trunnions as I8 substantially normal to the axis ofrotation thereof in opposite directions parallel with the axis of thedrive and driven shafts 4 and 5.

The advantage obtained by this construction over the constructiondescribed above for the clutch mechanism shown in Figures 3, 5, and 6resides in the fact that the drive shaft 4 and drive clutch member 'i2may be operating at a higher speed of rotation when the clutch elementsor rings I4 and I5 are moved from the idle or de-clutched position tothe clutch or operative position. 'Ihis advantage is obtained by reasonof the fact that the clutch elements or rings may be tilted or inclinedrelative to the axis of rotation of the driven shaft 5 when the sets oftrunnions 25 and I8 are at right angles to each other,

as illustrated by brokenlines in Figure l0, thus eliminating thenecessity of tilting'the clutch elements only when said sets oftrunnions are in coaxial alignment witheach other.. Y

When'the clutchelements are swung to the position illustrated lby'brokenlines in Figure 10 about the inner positioned trunnions I8 as an axis,there will be no clutching action between the clutch elements althoughsaid elements are in an inclined plane for the reason that the elementsare `free to rotate relative to each other due to the trunnions 25 beingpositioned at the outer ends of their respective slots 1|. It,therefore, follows that the clutch elements I4 and l5 may easily bemaintained in the inclined plane by pressure upon one of the clutchelements as through stud 3l during the succeeding substantiallyone-quarter revolution of the drive members 4 and 12. During thisquarter of revolution, the trunnions 25 will travel alo-ng the inclinedplane of the clutch elements and, in doing so, will freely move axiallyof the member 'l2 through the slots 1l until said trunnions reach thediametrical axis passing through the inner trunnions I8, at whichposition the o-uter trunnions 25 will be at the inner end of theirrespective slots in axial alignment with the inner trunnions I8.

Inasmuch as the outer trunnions are then at the inner ends of theirrespective slots, they will be maintained thereby against continuedmovement axially of the member 12 and be positively rotated by saidmember in a plane normal to the axis of shaft 5 even as when they aremounted in the manner shown in Figure 3. The clutch elements will thusbe prevented from further rotary movement relative to each other whilein the inclined plane so that they will then rotate in unison in a planenormal to the axis of rotation of shafts 4' and 5 and thereby positivelytransmit motion from the drive members to the driven members.

Although the `construction and operation of the mechanism shown anddescribed are particularly simple, practical, andV efficient, we do notwish to be limited to the exact construction shown as it is evident thatvarious changes may be made in the detailed construction withoutdeparting from the spirit of the invention as set forth in the appendedclaims.

We claim:

l. In a power transmission mechanism, the combination with a drivemember and a driven member mounted in co-axial relation, a. pair ofco-acting clutch elements, means pivotally connecting each of saidelements with a respective one of said members to move from a positionsubstantially normal to the axis of movement of the members to anangular position inclined to said axis of movement, .one of said pivotalmeans including diametrically disposed trunnions mounted for limitedmovement axially of the corresponding member from the diametrical planepassing through the other pivotal means to one side of said plane,whereby said clutch elements may be tilted when the pivotal meanstherefor are in angular relation to each other, stop means arrangedconcentric with the trunnions when said trunnions are in saiddiametrical plane of the other pivotal means for maintaining thetrunnions against movement axially of the member in the oppositedirection, whereby the clutch elements will be locked to eachother andthus caused to move in unison when in the tilting position, and meansfor moving the elements from the first to the second position.

2. In a power transmission mechanism, th 'combination with ra rotarydrivemember and `a rotary driven member, a clutch element having acircular recess therein, a second clutch element rotatably mounted in`said recess, means connected with each of the Clutch elements at,diametrically opposite sides thereof for pivotally connecting the sameto a respective one of said mem.- bers, means for rocking the clutchelements from a position substantially normal to the axis of movement ofthe drive and driven members to a position vinclined at an angle to saidaxis of movement whereby the clutch elements will be moved from aninoperative position where said elements may rotate relative to eachother to an operative position where the elements are maintained againstsaid relative movement so that motion is positively transmitted from thedrive element to the driven element, and rolling members mounted in saidrecess between said clutch elements whereby said clutch elements willoperate freely during said relative rotary movement thereof.

3. In a power transmission mechanism, the combination with a rotarydrive member and a rotary driven member, of a pair of coacting clutchelements, the rst of said clutch elements being mounted on one of themembers for tiltingmovement about a xed axis, separate means including apair of diametrically disposed trunnions connecting the second clutchelement to the other member to permit tilting action of said clutchelement in unison with the rst clutch element, said trunnions beingslidably connected with the corresponding member for axial movementrelative thereto in one direction to permit tilting of the clutchelement when said trunnions are in angular relation to the axis oftilting movement of the rst clutch element, and means for maintainingthe trunnions in co-axial alignment with the first mentioned pivotalmeans against axial movement relative to said member in the oppositedirection to effect locking of the clutch elements to each other whensaid elements are in the tilting position.

' 4. In a power transmission mechanism, in combination, a drive memberand a driven member mounted in co-axial relation therewith, a pair ofrelatively movable clutch elements, means including a single pair ofdiametrically opposed trunnions pivotally connecting one of the clutchelements with one of the members, means including a second single pairof diametrically opposed trunnions pivotally connecting the remainingclutch element and member to each other, one of said pairs of trunnionsbeing mounted in corresponding elongated guide slots provided in thecorresponding member, said slots extending in opposite directions fromthe plane passing through the other trunnions normal to the axis ofmovement of the drive and driven members to provide for a limitedmovement of the trunnions axially of the corresponding member, andYmeans for rocking the clutch elements about the trunnions as pivots tobring them into and out of clutch relation.

5. In a power transmission mechanism, the combination with a rotarydrive member and a rotary driven member, of a pair of co-,acting clutchelements, the first of said clutch elements being mounted on one of themembers for tilting movement about a xed axis, separate means associatedwith'the remaining clutch element and member co-acting to pivotallyconnect the same to each other including a trunnion and guide meanstherefor extending axially of the member whereby the clutch element isfree to ti1t in tilted position and the axis of the trunnion i's iriunison with the first clutch element when said alignment with said xedaxis to effect locking trunnion is positioned With the axis thereofnorof the clutch elements to each other, and means mal to said xed axis,stop means associated with for producing said tilting of the clutchelements. the guide means and oo-acting with the trun- ROBERT K. PEPPER.nion only when the clutch elements are in the SAMUEL C. V. PEPPER.

